Sediment and marine biota comprising several species of tidal flat and coastal organisms were analyzed for polychlorinated biphenyls (PCBs) including non- and mono-ortho coplanar congeners and polycyclic aromatic hydrocarbons (PAHs) to examine bioaccumulation profiles and toxic potencies of these contaminants. Concentrations of PCBs in tidal flat organisms ranged from 3.6 ng/g (wet wt) in clams to 68 ng/g (wet wt) in omnivore tidal flatfishes, a discernible trend reflecting concentrations and trophic levels. In contrast, PAHs concentrations were the highest in lower trophic organisms, such as crabs and lugworms from tidal flat, whereas those in coastal fishes, squid, and finless porpoises were less than detection limit. Greater bioaccumulation of PAHs was found in lugworms and crabs, which might be due to their direct ingestion of sediment particulates absorbed with PAHs. TCDD toxic equivalents (TEQs) were calculated for PCBs and PAHs in sediments and biota. PCBs accounted for a greater proportion of total TEQs (sum(TEQs): sum of TEQ(PCB) and TEQ(PAH)) in coastal and tidal flatfishes (>95%), while PAHs occupied a considerable portion of sum(TEQs) in sediment (>97%). Interestingly, TEQ(PAH) accounted for 37% and 81% of the sum(TEQs) in crabs and clams, respectively. Benzo[b]fluoranthene was the dominant contributor to TEQ(PAH) in both the species. Considering these observations, the environmental risks of PAHs may not be ignored in benthic tidal flat organisms due to their greater bioaccumulation through sediments.

Molecular oxygen serves as a useful oxidant for the glycol scission of 1,2-diols and the Hofmann rearrangement of primary amides using pentamethyliodobenzene as a catalyst. The use of isobutyraldehyde and Lewis basic nitriles under O enabled the iodine(i)/(iii) catalytic cycle, where in situ-generated peracid acts as a terminal oxidant.

The first catalytic version of hypervalent aryl-λ(3)-iodane-induced Hofmann rearrangement of primary carboxamides, which probably involves in situ generation of a tetracoordinated bis(aqua)(hydroxy)phenyl-λ(3)-iodane complex as an active oxidant from a catalytic amount of iodobenzene by the reaction with m-chloroperbenzoic acid in the presence of HBF(4) in dichloromethane-water under mild conditions, was developed.

No abstract

Pyrolysis of bis(perfluoroalkanesulfonyl)bromonium ylides in various olefins results in highly stereospecific formation of cyclopropanes via unimolecular decomposition. Product analysis, kinetic study, substituent effects, and theoretical study revealed the generation of singlet bis(perfluoroalkanesulfonyl)carbenes stabilized by intramolecular coordination of sulfonyl oxygen.